1. Field of the Invention
The present invention relates to a new and novel reinforced primary backing made primarily of woven polypropylene where the backing is reinforced in the warp direction by weaving yarns other than polypropylene into the backing at predetermined intervals across the width. The other yarn in order to impart the requisite improved dimensional stability to the backing will either be non-stretchable or less stretchable than polypropylene.
2. Description of the Prior Art
In recent years, tufted pile fabrics utilizing primary and secondary backings made from synthetic plastic materials have been developed for use indoors and outdoors. These carpets have utilized synthetic plastic primary and secondary backings in order to provide stability to the carpet structure and to eliminate the problems encountered previously by carpets which have been made from natural fibers. Carpets made from natural fibers are subject to shrinking and rotting in abnormal weather conditions and when liquids are spilled thereon. Additionally, such carpets are subject to excessive staining and require frequent removal and cleaning.
In U.S. Pat. No. 3,110,905 issued Nov. 19, 1963 to Rhodes and U.S. Pat. No. 3,336,178 issued Aug. 15, 1976 to Levitch, and both assigned to the same assignee as the instant application, namely, Burlington Industries, Inc., there are disclosed tufted pile fabrics utilizing synthetic plastic backings and pile yarn also made from synthetic plastic or man-made fibers. While the tufted pile fabric disclosed in these two patents have been commercially successful for installations wherein the floor covering is subjected to rotting conditions, moisture conditions from rain or spillage of liquids, they have not been completely satisfactory when used in situations wherein the carpeting is to be substantially permanently installed by adhesively securing the same to a floor structure, particularly when the primary and secondary backings are bonded together with a hot melt adhesive. With the advent of the use of hot melt adhesives and the application of such technology to the disclosures in these two patents and particularly to the disclosure in Levitch, the resulting tufted pile fabric provided greatly improved adhesion between the synthetic primary and secondary backings, effectively preventing separation of the primary and the carpet face from the secondary, when the secondary is bonded to a floor structure. Additionally, the hot melt adhesive greatly improves pile bind, effectively preventing removal of carpet tufts from the carpet face by pulling or snagging.
U.S. Pat. No. 3,110,905 to Rhodes discloses the basic woven synthetic primary carpet backing. In essence, such a primary backing is formed of a flat weave of synthetic yarns in which every point on the primary backing is of substantially uniform thickness. While, Rhodes teaches the use of any synthetic yarn capable of being spun, extruded, or shaped into a flattened or rectangular shape, polypropylene and polyethylene are disclosed as most suitable. Other suitable synthetic yarns which are listed in the Rhodes patent are acrylic, modacrylic, polyester, nylon, rayon, acetate, triacetate, cellulosic, vinyl, vinylidene, chloride and polyvinyl chloride. However, in actuality, the most commonly used woven synthetic primary backings are made entirely of polypropylene yarns employed for both the warp and weft.
As discussed hereinabove, polypropylene primary backings are used in various hot melt processes. During the course of applying hot melt resins to carpets having polypropylene primary backings the heat from the hot resin renders the polypropylene primary backing susceptible to stretchings in the machine direction, i.e., length direction, during subsequent process steps thereby losing a portion of its dimensional stability.
The stretching imparts instability to the carpet product particulary when the carpet is cut and sold as carpet tiles. This instability, in turn, leads to excess shrinkage, cupping and domeing of the carpet or carpet tiles.
While there have been various attempts to improve the dimensional stability of backings, e.g., U.S. Pat. Nos. 4,296,159, 4,242,394, 4,123,577 and 4,131,704, none of these appear to have efficiently and economically solved the stretching of polypropylene backings caused by a hot melt resin application.
Therefore, it is the object of the present invention to overcome the stretching problem and the resultant decrease in dimensional stability discussed hereinabove.